By default when accessing any directory which does not contain an index file on a cPanel server (ex: https://yourdomain.com/images/) a directory listing will be shown displaying a list of the files in that folder. Simply adding a blank/0 byte text file named "index.html" will prevent this directory list from being displayed, however another way to disable directory listings is by adding the following line to the .htaccess file in your public_html folder:
Options -Indexes
That's it, with this line in place folders which do not contain index files will no longer show the default directory list.
On DirectAdmin servers, directories which do not contain an index file will display a "403 Forbidden" message by default. To enable the directory listing feature you will want to add the following line of code to the .htaccess file in your public_html folder:
Options +Indexes